[Scons-dev] New symlink copy support

[anatoly techtonik]

On Wed, Jul 30, 2014 at 3:43 AM, William Blevins <wblevins001 at gmail.com> wrote:
>>  2. Get Mercurial and run tests in VM
>>       hg clone http://selenic.com/hg
>>       cd hg/contrib/vagrant
>>       vagrant up
>>       vagrant ssh -c ./run-tests.sh
>>
>> Vagrant mounts current folder as /vagrant inside VM, so when I cd to this
>> folder and try to create symlink, I get a nasty error:
>>
>>     vagrant ssh
>>
>>     $ cd /vagrant
>>     $ ln config.yml config.yml2
>>     ln: failed to create hard link `config.yml2' => `config.yml':
>> Operation not permitted
>>     $ ln -s config.yml config.yml2
>>     ln: failed to create symbolic link `config.yml2': Protocol error
>>     $ python -c "import os; os.symlink('config.yml', 'config.yml2')"
>>     Traceback (most recent call last):
>>       File "<string>", line 1, in <module>
>>     OSError: [Errno 71] Protocol error
>
>
> I've never used vagrant before, but it was fairly intuitive with your
> example.
>
> 1. run-tests.sh is still executing after 30min+ and there are some errors,
> but nothing I can see related to symlinks.
> 2. I was able to create symlinks inside the "/vagrant" directory

Sorry if I was not clear. This was just to demonstrate the modern
development setup with Vagrant. The type of file system mounted
as "/vagrant" is your host FS. In my case it is Windows, so I get
this error.

> Based on this example, I don't think your use case makes sense.  In order
> for the SCons Copy code to fail on "os.symlink", Copy must be attempting to
> copy a symlink:
>
>> ls -l
>> lrwx------ item -> item.txt
>> -rwx------ item.txt
>> cat SConstruct
>> Copy( 'item', 'item_link', True ) # default is True anyway
>> Copy( 'item', 'item_file', False ) # default is True anyway
>> scons
>    Copy( item, item_link )
>    Copy( item, item_file )
>> ls -l
>> lrwx------ item -> item.txt
>> -rwx------ item.txt
>> lrwx------ item_link -> item.txt
>> -rwx------ item_file
>> echo "item.txt & item_file inode count is 1"
>
> Copy does not try to create a symlink from a "real" file:

I see, I missed this fact from the commit. That makes sense,
but documentation needs to be simplified IMO.

https://bitbucket.org/scons/scons/commits/2e225b46b2ad10230ae0a11090a7a26101866989

Because I read "symbolic link copying behavior" in a wrong way.

> Maybe it was just a bad example? You could still have this issue if you are
> copying a symlink from a filesystem that supports it to one that doesn't.

Also in Windows you can not create link from one drive to other even
if FS supports it.